1. Field of the Invention
The present invention relates to a speed control device for a ceiling fan, more particularly, to a speed control device which adopts a MOSFET as a power control element to control the operation of a ceiling fan thereby providing advantages of stability, simplicity and low cost.
2. Description of Related Art
Conventionally, the speed control device of a ceiling fan makes use of a transformer or capacitor in cooperation with a switch or Triac to control the speed of a ceiling fan. However, the use of the transformer and capacitor, which are large and heavy, will significantly increase the weight of the ceiling, fan and thus cause a safety problem as the ceiling fan is hung on a ceiling. Moreover, if multi-speed control is desired, the speed control device must have a plurality of Triacs, which further increases the weight of the ceiling fan and makes the safety problem even worse. Another conventional speed control device for controlling the speed of a ceiling fan is to adopt a Triac to control the phase of power source. Although this conventional speed control device is simple in structure, it causes the motor of the ceiling fan to generate lots of noise when rotating. Therefore, there is a need for the above ceiling fan speed control device to be improved.